[Blindmath] Extracting bitmap images from pdf files

Sat Jan 28 23:40:11 UTC 2012

Hi Richard and others,

I had my assistant take the Chapter 18 physics textbook PDF  you sent 
and do what he typically does for me with PDF images.

We used the Acrobat Professional's Document > Crop command to crop 
just the battery.  The borders were selected with a mouse by a 
human.  The resulting battery.pdf file is attached.  I believe 
Acrobat blew it up to a much larger size than the very small image it 
was in the original text.

We then investigated the Advanced > Export All Images command.  We 
varied the image size threshold setting from none to 2" and got 
anywhere from 0 to 54 images off that page, mostly little dots, plus 
signs, triangles, etc. but no intact battery image.

We used the same Advanced > Extract All Images command on a page with 
a picture, I think a man charging a car battery, and this worked beautifully.

So what to conclude???  Raster graphics extract nicely.  Vector 
graphics are not kept intact.  Vector graphics must be cropped and 
made into another PDF using the mouse to select borders.

Now, admittedly, our copy of Acrobat Pro is old - it's version 
7.  But I'm not convinced newer versions of Adobe products are any 
more useful than their old ones, if anything, they are more difficult to use.

So ... The Iveo solution seems to be the better solution at the moment.

Ben

At 08:59 AM 1/28/2012, you wrote:

But, no, I do not believe we were dealing with PDFs in this case.

Typically, when we have a PDF with a graphic, my assistant draws a 
box around it I think and saves it out separately.  I'm not clear on 
the process but he did say it required Acrobat Pro and once it's 
extracted, it's easy to blow it up to fill the page for easier 
tactile understanding.

>Hi Ben,
>
>I appreciate your frustration.
>
>Were the  "30 itty bitty graphics files" that apparently were small parts
>of two actual graphs produced using Acrobat Pro, or were you using some
>different image extraction software during that lost weekend?
>
>Thanks,
>Dick Baldwin
>
>On Sat, Jan 28, 2012 at 5:55 AM, Ben Humphreys 
><brh at opticinspiration.org>wrote:
>
> > I suppose this procedure could work.
> >
> > But when it's this much effort to get to the starting gate, while other
> > students are already moving forward and you're falling behind, it's no fun,
> > and the added time and complexity and brainpower just takes all the
> > motivation out of you.
> >
> > I remember losing a whole weekend to the issue of 30 itty bitty graphics
> > files in a Calculus PDF.  Having embossed them, they were all told to "fit
> > to page" and were thusly huge.  I was thinking they were all graphs and
> > problems to be interpreted and worked on and understood, only to be told
> > later that there were only two graphs and having the benefit of a sighted
> > person on Monday morning to finally tell me that they were bits and pieces
> > of the two relatively simple graphs.
> >
> > It's enough to make you want to be a Steve Jobs and exit school
> > prematurely.
> >
> > Prof Baldwin, this is certainly not to say I don't appreciate all your
> > effforts.  In fact, if and when I ever need to take physics, I am seriously
> > considering relocating to Austin for a semester.
> >
> > P.S. I do have Acrobat pro so if you can send me the single page PDF in
> > question, we can attempt to extract as a single image.
> >
> > Ben
> >
> >
> > At 02:56 PM 1/27/2012, you wrote:
> >
> >> In a previous post I wrote:
> >>
> >> "By the way, I don't know how a blind person would carry out the second of
> >> the following two steps in John's procedure:
> >>
> >> * import the PDF into IVEO Creator Pro.
> >> * Check the PDF to find which pages have images of interest and emboss
> >> those
> >> pages.
> >>
> >> It seems that checking the pdf to find which pages have images would be
> >> similar to checking a screen shot of a page to find and crop the image. It
> >> seems that you would need to be able to see the pdf on the IVEO screen to
> >> know if it contains an image. I am working with pdf files containing
> >> anywhere between 30 and 80 pages. Embossing every page in order to
> >> identify
> >> the pages that contain images would not be practical."
> >>
> >> I have learned how a blind person could find the pages containing the
> >> images in a pdf file without having to see the screen. Here is one
> >> procedure for doing that.
> >>
> >> When you import a pdf file into Creator Pro, a set of SVG files is
> >> automatically created in the folder than contains the pdf file. There is
> >> one SVG file for each page in the pdf file. The file names indicate the
> >> pdf
> >> page number except that pages in a pdf file are typically numbered
> >> beginning with 1 while the file numbers produced by Creator Pro begin with
> >> 0. Thus, file number 0 will probably correspond to page 1 in the pdf
> >> document.
> >>
> >> Read the pdf file in your preferred pdf file reader. If from the pdf text,
> >> you can determine which pages in the pdf file contain images of interest,
> >> you can record those page numbers using whatever method you use to record
> >> information of that sort.
> >>
> >> Then you can import the pdf file into Creator Pro, producing the set of
> >> SVG
> >> files described above. Then you can open the SVG files that contain
> >> interesting images in your IVEO viewer software, emboss the pages, and
> >> proceed as John explained in an earlier post.
> >>
> >> Dick Baldwin
> >>
> >> On Fri, Jan 27, 2012 at 12:47 PM, Richard Baldwin
> >> <baldwin at dickbaldwin.com>**wrote:
> >>
> >> > Michael wrote " There is one option I am aware of for a blind person to
> >> > do this independently, IVEO like John suggested,"
> >> >
> >> > I may be wrong, but I didn't get the idea that John's solution will
> >> > produce an output bitmap file - only an embossed image.
> >> >
> >> > I may be wrong again, but as near as I can tell, IVEO doesn't do any
> >> image
> >> > enhancement prior to embossing the image. If I am wrong on these points,
> >> > John will probably come online and set the record straight.
> >> >
> >> > IVEO seems to simply convert the bitmap image to gray scale and emboss
> >> the
> >> > gray scale. While gray scale embossing is okay for some images
> >> (especially
> >> > blank and white images), it is definitely not the best option for many
> >> > images. After all, if you convert 16 million colors to four levels of
> >> gray
> >> > scale, each level of gray scale represents 4 million different colors.
> >> > Pixels belonging to each set of 4 million colors will not be
> >> > distinguishable in the gray scale representation.
> >> >
> >> > My objective is to gain access to full-color bitmap images so that I can
> >> > enhance the image for embossing prior to throwing away all of the color
> >> > information.
> >> >
> >> > Embossed versions of bitmap images are often very difficult to
> >> understand,
> >> > even with a decent description. I believe we need to do everything
> >> > reasonable to improve the understandability of embossed bitmap images.
> >> In
> >> > some cases, image enhancement techniques at the full-color stage can be
> >> > used to provide those improvements.
> >> >
> >> > So, my quest continues, hopefully without having to pay $445.00 for
> >> > Acrobat Pro, just to get access to the images.
> >> >
> >> > The fallback position, of course, is to use screen shots and an image
> >> > editor program to crop out the individual images, but that approach is
> >> not
> >> > possible for a blind person to use. You can't crop an image out of a
> >> screen
> >> > shot unless you can see the image.
> >> >
> >> > By the way, I don't know how a blind person would carry out the second
> >> of
> >> > the following two steps in John's procedure:
> >> >
> >> > * import the PDF into IVEO Creator Pro.
> >> > * Check the PDF to find which pages have images of interest and emboss
> >> > those
> >> > pages.
> >> >
> >> > It seems that checking the pdf to find which pages have images would be
> >> > similar to checking a screen shot of a page to find and crop the image.
> >> It
> >> > seems that you would need to be able to see the pdf on the IVEO screen
> >> to
> >> > know if it contains an image. I am working with pdf files containing
> >> > anywhere between 30 and 80 pages. Embossing every page in order to
> >> identify
> >> > the pages that contain images would not be practical.
> >> >
> >> > Dick Baldwin
> >> >
> >> >
> >> > On Fri, Jan 27, 2012 at 11:48 AM, Richard Baldwin <
> >> baldwin at dickbaldwin.com
> >> > > wrote:
> >> >
> >> >> Amanda and others,
> >> >>
> >> >> I have contacted Adobe technical support. There solution to the problem
> >> >> is to purchase Acrobat Pro for $445.00. The tech support rep told me
> >> that
> >> >> their program will extract the pictures intact as separate bitmap
> >> files.
> >> >>
> >> >> Dick Baldwin
> >> >>
> >> >>
> >> >> On Fri, Jan 27, 2012 at 10:44 AM, Michael Whapples <mwhapples at aim.com
> >> >wrote:
> >> >>
> >> >>> Hello,
> >> >>> From what you are describing, my feeling is that the diagrams/images
> >> in
> >> >>> the PDF in question are created from a number of drawing elements
> >> rather
> >> >>> than a single image object. I'm not an expert on PDF, but I think you
> >> could
> >> >>> think of it like the difference of a bitmap being a single element (I
> >> think
> >> >>> PDF has a way to specify the start of a stream object like a bitmap)
> >> and an
> >> >>> SVG being formed from lots of elements like lines and shapes (I think
> >> in
> >> >>> PDF the lines and such like can be created with basic PDF drawing
> >> >>> facilities so are not in a separate object). When the image is formed
> >> from
> >> >>> lots of elements then it may be hard for the software to know what
> >> makes up
> >> >>> a given diagram in the book/document, it just lays it out as
> >> specified and
> >> >>> you work out what's related. I think one way to tell whether you have
> >> this
> >> >>> sort of image is to see if NVDA will read some of the text labels of
> >> the
> >> >>> image, if it does then its not a pure bitmap (you probably could use
> >> the
> >> >>> read out lout function of adobe reader as well). Therefore I imagine
> >> that
> >> >>> without clever recognition algorithms you are unlikely to get
> >> something
> >> >>> which will extract it as you want.
> >> >>>
> >> >>> There is one option I am aware of for a blind person to do this
> >> >>> independently, IVEO like John suggested, however IVEO isn't a cheap
> >> option
> >> >>> and depending on how much is to be done would determine whether its
> >> worth
> >> >>> the money if providing accessible diagrams from PDF was its only use.
> >> IVEO
> >> >>> does not require a tiger printer, swell paper would work, other
> >> embossers
> >> >>> may (the outputting from IVEO is the question as I think it may only
> >> output
> >> >>> to devices appearing as standard printers). Interesting, the IVEO
> >> route
> >> >>> again is requiring a human to make the decision on what forms the
> >> diagram.
> >> >>>
> >> >>> Michael Whapples
> >> >>>
> >> >>> -----Original Message----- From: Richard Baldwin
> >> >>> Sent: Friday, January 27, 2012 3:28 PM
> >> >>> To: Jamal Mazrui
> >> >>> Cc: Blind Math list for those interested in mathematics
> >> >>> Subject: Re: [Blindmath] Extracting bitmap images from pdf files
> >> >>>
> >> >>>
> >> >>> Hi Jamal,
> >> >>>
> >> >>> It is a great program, easy to use, and probably totally accessible. I
> >> >>> particularly like the fact that the program doesn't require a windows
> >> >>> installation. The output data is well organized and including the page
> >> >>> numbers in the bmp file names is a great help in analyzing them.
> >> >>>
> >> >>> Unfortunately, the output produced by the program suffers from the
> >> same
> >> >>> issues that I have encountered with all of the other image extractor
> >> >>> programs that I have tried. A few of the images come out intact. Most
> >> of
> >> >>> the images don't come out intact.
> >> >>>
> >> >>> For example, page three of one of the pdf files that I tested has a
> >> >>> single
> >> >>> image of a battery. It is the same image that I enhanced and posted
> >> in an
> >> >>> earlier post. Your program produced 54 bmp files for that page. A few
> >> of
> >> >>> them were icons such as arrows exclamation marks, etc. The remaining
> >> bmp
> >> >>> files appear to be a very small pieces of the image of the battery. By
> >> >>> the
> >> >>> way, I got the earlier image of the battery by taking a screen shot of
> >> >>> the
> >> >>> page and using an image editing program to crop out the battery image.
> >> >>> None
> >> >>> of the image extraction programs that I have tested extract the image
> >> >>> intact.
> >> >>>
> >> >>> I don't know anything at all about the internal structure of pdf
> >> files,
> >> >>> and
> >> >>> this behavior of breaking an image into many small pieces may depend
> >> on
> >> >>> how
> >> >>> the file is constructed in the first place. In any event, my immediate
> >> >>> problem has to do with a specific set of pdf files that are the
> >> chapters
> >> >>> from a specific physics book, so this program doesn't solve my
> >> problem.
> >> >>>
> >> >>> Thanks for offering the program.
> >> >>> Dick Baldwin
> >> >>>
> >> >>> On Fri, Jan 27, 2012 at 5:18 AM, Jamal Mazrui <empower at smart.net>
> >> wrote:
> >> >>>
> >> >>>  In an attempt to facilitate a free, non-web dependent solution, I
> >> have
> >> >>>> written a Windows console-mode utility called PDF2Images, built with
> >> >>>> PowerBASIC and a PDF library.  The distribution archive, including
> >> >>>> documentation and source code, is available at
> >> >>>>
> >> >>>> 
> http://empowermentzone.com/******pdf2images.zip<http://empowermentzone.com/****pdf2images.zip>
> >> 
> <http://**empowermentzone.com/****pdf2images.zip<http://empowermentzone.com/**pdf2images.zip>
> >> >
> >> >>>> 
> <http://**empowermentzone.com/****pdf2images.zip<http://empowermentzone.com/**pdf2images.zip>
> >> 
> <http://**empowermentzone.com/**pdf2images.zip<http://empowermentzone.com/pdf2images.zip>
> >> >
> >>
> >> >>>> >
> >> >>>>
> >> >>>>
> >> >>>> I am interested in any feedback on how well it works compared to
> >> other
> >> >>>> approaches.
> >> >>>>
> >> >>>> Jamal
> >> >>>>
> >> >>>>
> >> >>>>
> >> >>>>
> >> >>>
> >> >>> --
> >> >>> Richard G. Baldwin (Dick Baldwin)
> >> >>> Home of Baldwin's on-line Java Tutorials
> >> >>> http://www.DickBaldwin.com
> >> >>>
> >> >>> Professor of Computer Information Technology
> >> >>> Austin Community College
> >> >>> (512) 223-4758
> >> >>> mailto:Baldwin at DickBaldwin.com
> >> >>> 
> http://www.austincc.edu/****baldwin/<http://www.austincc.edu/**baldwin/><
> >> http://www.austincc.edu/**baldwin/ <http://www.austincc.edu/baldwin/>>
> >> >>> ______________________________****_________________
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> >>
> >> >>>
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> Richard G. Baldwin (Dick Baldwin)
> >> >> Home of Baldwin's on-line Java Tutorials
> >> >> http://www.DickBaldwin.com
> >> >>
> >> >> Professor of Computer Information Technology
> >> >> Austin Community College
> >> >> (512) 223-4758
> >> >> mailto:Baldwin at DickBaldwin.com
> >> >> http://www.austincc.edu/**baldwin/ <http://www.austincc.edu/baldwin/>
> >> >>
> >> >
> >> >
> >> >
> >> > --
> >> > Richard G. Baldwin (Dick Baldwin)
> >> > Home of Baldwin's on-line Java Tutorials
> >> > http://www.DickBaldwin.com
> >> >
> >> > Professor of Computer Information Technology
> >> > Austin Community College
> >> > (512) 223-4758
> >> > mailto:Baldwin at DickBaldwin.com
> >> > http://www.austincc.edu/**baldwin/ <http://www.austincc.edu/baldwin/>
> >> >
> >>
> >>
> >>
> >> --
> >> Richard G. Baldwin (Dick Baldwin)
> >> Home of Baldwin's on-line Java Tutorials
> >> http://www.DickBaldwin.com
> >>
> >> Professor of Computer Information Technology
> >> Austin Community College
> >> (512) 223-4758
> >> mailto:Baldwin at DickBaldwin.com
> >> http://www.austincc.edu/**baldwin/ <http://www.austincc.edu/baldwin/>
> >> ______________________________**_________________
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> >
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>
>--
>Richard G. Baldwin (Dick Baldwin)
>Home of Baldwin's on-line Java Tutorials
>http://www.DickBaldwin.com
>
>Professor of Computer Information Technology
>Austin Community College
>(512) 223-4758
>mailto:Baldwin at DickBaldwin.com
>http://www.austincc.edu/baldwin/
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